Roller for a machine for producing and/or processing a paper, cardboard, or tissue web, and method for operating the roller

ABSTRACT

A roll for a machine for producing or processing a fibrous web includes a movable roll shell, a positive or negative pressure zone which is disposed within the roll shell and is rotationally fixed relative to the roll shell, and a sealing device for sealing the positive or negative pressure zone from the surroundings. The sealing device has a sealing strip and a lubricating device with which a lubricant can be introduced between the inner surface of the roll shell and the sealing surface of the sealing strip. The lubricating device includes a plurality of lubricant outlet openings and is connected to a supply line for supplying lubricant through a plurality of inlet segments. The supply line includes an inner section which runs within the roll shell, the inner section having a storage volume of at least 490 cm3/m. A method for operating a roll is also provided.

The invention relates to a roll for a machine for producing and/orprocessing a fibrous web according to the preamble of claim 1, and amethod for operating the roll according to the preamble of claim 13.

Sealing devices in evacuated or blown rolls of paper, board or tissuemachines must reliably seal off the positive or negative pressure zoneagainst the surroundings in which normal pressure prevails. Here, toseal the positive pressure or negative pressure zone, the sealingsurface of each sealing strip of the sealing device is set against theinside of the rotating roll shell. In order to reduce the wear of thesealing strip caused by friction between the lateral surface and thesealing surface, attempts are made to introduce lubricant between thesealing surface and the inside. This is usually done with spray pipeswhich, in the direction of rotation of the roll, are arranged upstreamof the first sealing strip of the positive or negative pressure zone.Here, the lubricant applied to the inside of the roll shell is conveyedby the rotation of the latter to the individual sealing strips, as aresult of which, as seen in the direction of rotation, the lubricantsupply decreases from sealing strip to sealing strip. In ordernevertheless to supply the sealing strips following in the direction ofrotation with sufficient lubricant, a large quantity of lubricant has tobe used, which, however, benefits only a small part of the actuallubrication of the sealing strips and otherwise contributes only to theundesired re-wetting of the fibrous web.

To solve this problem, EP 2 885 457 and EP 3 022 356 propose to conductthe lubricant directly to the upper side of the respective sealing stripproviding the sealing surface, in order thereby to supply eachindividual sealing strip specifically with the necessary quantity oflubricant. A preferred refinement of this invention here also proposes alubricant channel, provided on the upper side of the roll in the form ofa groove-like depression arranged on the sealing surface and extendingin the longitudinal direction of the sealing strip, i.e. in thecross-machine direction of the roll, if necessary with the aid of asuitable lip.

Irrespective of which type of lubricating device is used, it isessential for low-wear operation of such a roll that the sealing surfaceof the sealing strip is adequately supplied with lubricant over itsentire length, which is frequently 10 m or more. However, as small aquantity of lubricant as possible should be used for this lubrication,for economic reasons.

For this purpose, it would be desirable to be able to ensure the mostuniform distribution of the lubricant as possible over the entire lengthof the sealing strip.

It is therefore an object of the invention to propose a roll having asealing device in which a uniform supply of the sealing strip withlubricant is ensured. Furthermore, it is an object of the invention toindicate a reliable method for operating such a roll while using a smallquantity of lubricant.

With regard to the roll, the object is completely achieved by a roll fora machine for producing or processing a fibrous web according to thecharacterizing part of claim 1 and, with regard to the method, by amethod for operating a roll for a machine for producing or processing afibrous web according to the characterizing part of claim 13.

Further advantageous embodiments are described in the sub-claims.

A roll is proposed for a machine for producing or processing a fibrousweb, which comprises a movable roll shell and a positive or negativepressure zone which is arranged within the roll shell and is fixedagainst rotation relative to the roll shell, and a sealing device forsealing off the positive or negative pressure zone with respect to thesurroundings. The sealing device here has a sealing strip and alubricating device, by means of which a lubricant can be introducedbetween the inside of the roll shell and the sealing surface of thesealing strip, wherein the lubricating device comprises a plurality oflubricant outlet openings and is connected via multiple inlet segmentsto a supply line for the supply with lubricant. According to theinvention, the roll is characterized in that the supply line comprisesan inner section which extends within the roll shell, and this innersection has a storage volume of at least 490 cm³/m, in particular atleast 500 cm³/m, in particular of at least 750 cm³/m or 1000 cm³/m,based on the length of the sealing strip.

An inlet segment is intended to be understood to be a line part which isconnected to the supply line which supplies the entire lubricatingdevice and conducts lubricant to some of the lubricant outlet openings.

Trials by the applicant have surprisingly shown that, with such a supplyline of the sealing device, a uniform lubricant distribution can beimplemented. As a result of the buffering action of the comparativelylarge storage volume of the supply line, it is possible to ensure thatall the inlet segments are supplied with the same pressure, or that thepressure difference is at least so small that it has no noticeableinfluence on the distribution of the lubricant. This represents asignificant difference from the rolls known from the prior art. There, anormally thin supply line is led into the roll from one side, and theinlet segments to the lubricating device branch off from this supplyline. This leads to a noticeably lower pressure being present in theinlet segments located further downstream in the flow direction of thelubricant and a smaller quantity of lubricant being supplied to thelubricating device. This effect is largely avoided by the storage volumein the present roll.

The size of the storage volume should be at least 490 cm³/m, inparticular at least 500 cm³/m. The value of 490 cm³/m or 500 cm³/m issufficient for the quantities of lubricant of 0.5 l/m/min to about 3l/m/min that are normally used. Larger storage volumes of 1000 cm³/m,2000 cm³/m or more are advantageous for reasons of evening out thepressure, as described above. Because of the quite restrictedinstallation space in some rolls, or for economic reasons, it may beexpedient to limit the size of the storage volume of fluid. Thus, it maybe advantageous to provide the storage volume to be no greater than20,000 cm³/m or than 10,000 cm³/m.

The statement of the storage volume in “cm³/m” relates respectively tothe length of the lubricated sealing strip. Advantageously, the roll canbe designed as a suction roll. In such suction rolls, the roll shell hasopenings which are usually arranged in the form of a regular pattern.Thus, by means of the negative pressure prevailing in the negativepressure zone, water can be extracted from a fibrous web or clothingthrough the openings in the roll shell.

In an advantageous embodiment of the invention, provision can be madefor the inner section to comprise a pipe-shaped part or to consistthereof, which extends substantially over the entire length of thesealing strip, wherein this pipe has an internal diameter of 25 mm ormore at at least one point, in particular more than 40 mm, preferably 50mm or more. Such an embodiment is advantageous since, in this way, twoproperties of the supply line are simultaneously fulfilled, namely thedistribution of the lubricant over the length of the roll and thesealing strip and the provision of the storage volume. In particular,provision can advantageously be made that the pipe has a constant crosssection over more than 50% of its length, in particular over its entirelength. A pipe which has an internal diameter of 25 mm over the entirelength provides, for example, about 490 cm³/m, that is to say around 500cm³/m of storage volume. In another advantageous embodiment, provisioncan be made for the pipe to taper continuously over its length. Such anembodiment can be advantageous in particular in the case of long sealingstrips of more than 5 m or more than 10 m, in order to keep the pressurestill further constant on inlet segments placed downstream in the flowdirection of the lubricant.

In preferred embodiments, provision can further be made for theplurality of the lubricant outlet openings to be distributed uniformlyover the length of the sealing strip and, in particular, for thespacings of adjacent lubricant outlet openings to differ by less than25% or less than 10%. In addition to the uniform supply of the inletsegments, a distribution of the lubricant outlet openings of this typealso assists the uniform distribution of the lubricant over the entirelength of the sealing strip.

Advantageously, the spacing of two adjacent lubricant outlet openingscan be between 20 mm and 200 mm, in particular between 30 mm and 100 mm.In particularly preferred embodiments, the spacing of adjacent lubricantoutlet openings is between 40 mm and 60 mm.

The lubricating device can be implemented, for example, by lubricantbeing guided from the inlet segments to nozzle devices, for example fannozzles, which represent the lubricant outlet openings. Via the nozzles,the lubricant is lubricated in the direction of the sealing surface tobe lubricated. These nozzle devices are known as lubricating spray pipesand are usually arranged upstream of the sealing strip in the directionof rotation of the roll.

However, it may also be advantageous for the lubricating device to beprovided wholly or partly in or on the sealing strip, wherein inparticular the lubricant outlet openings are located in the sealingstrip. Sealing strips of this type with an integrated lubricating deviceare therefore frequently preferred since the lubrication of the sealingsurface can be implemented with a smaller quantity of lubricant.

Provision can also be made for the inner section to be designed to be atleast partly rigid. Here, the term “rigid” is to be understood incomparison with the inlet segments. Frequently, inlet segments aredesigned wholly or at least partly as a plastic hose. This is expedientin particular in sealing strips with an integrated lubricating device,since the inlet segment must move together with the movement of thestrip caused by the wear. For reasons of stability and simpler handling,it may be advantageous if the inner section of the supply line is atleast partly made from a rigid material, e.g. in the form of a metallicpipe or a plastic pipe.

Frequently, sealing devices have a so-called holder for holding thesealing strip. In a preferred embodiment, provision can be made for theinner section to extend at least partly on or in this holder.

In preferred embodiments, provision can be made for all the inletsegments to have the same length or to differ by less than 25% in theirlength. In the event of excessively large differences in the lengths ofthe inlet segments, there may be the danger that the action of eveningout the pressure, achieved by the invention, cannot be passed oncompletely as far as the lubricant outlet openings. Advantageously, thelength of the inlet segments can be between 150 mm and 700 mm, inparticular between 200 mm to 400 mm.

It is a very advantageous embodiment here if the inner section of thesupply line is mounted on the outside of the suction box of a negativepressure zone. Firstly, this mounting position is more easily accessiblethan in the interior of the suction box. Secondly, the distance from theinner section of the supply line to the inlets of the sealing strip isusually smaller, so that it is possible to manage with shorter inletsegments having a length of, for example, 150 mm-250 mm.

The spacing of an inlet segment from an end of the sealing strip on thelongitudinal side can preferably be at most 800 mm, in particular atmost 600 mm, preferably 400 mm or less.

Alternatively or additionally, provision can be made for the inletsegments to be arranged such that their spacing from one another in thelongitudinal direction of the roll is less than 2 m, in particular lessthan 1.75 m, preferably 1.5 m or less. In particular, the inlet segmentscan also be arranged such that the spacing of adjacent inlet segmentsfrom one another in the longitudinal direction of the roll is equal ordiffers only by less than 15%, in particular less than 5%.

Furthermore, it may be advantageous if the supply line additionally hasan outer section, which extends substantially outside the roll, whereinthe outer section, having an internal diameter of 25 mm or less, inparticular 20 mm or less, or 15 mm or less, is guided via an end faceinto the interior of the roll, where it is connected to the innersection. In particular, the outer section can have a lower internaldiameter than the inner section, in particular also at the connectingpoint of the two sections.

With regard to the method, the object is achieved by a method foroperating a roll for a machine for producing or processing a fibrousweb, wherein the roll is designed according to one of the previousclaims, characterized in that the lubricating device is supplied withless than 2.4 l/min/m, in particular between 0.4 l/min/m and 1.5l/min/m, of lubricant. Given such a quantity of lubricant, the rollaccording to one of the aforementioned aspects proves to be particularlyadvantageous.

Furthermore, it may be advantageous that, over a starting time period,the lubricating device is supplied with a first quantity of lubricantand, after this starting time period, the lubricating device is suppliedwith a second quantity of lubricant, wherein the first quantity oflubricant is greater, in particular more than 25% greater, than thesecond quantity of lubricant—in each case based on l/min/m.

Thus, for example, over a starting time period, the lubricating deviceis supplied with 2.4 l/min/m or more of lubricant and, after thestarting time period, the quantity of lubricant is reduced to less than2.4 l/min/m, in particular between 0.4 l/min/m and 1.5 l/min/m.

Such a starting time period can be, for example, at least 30 s, inparticular between 30 s and 5 min. Such a starting time period, whichprecedes the standard operation, can ensure, amongst other things thatthe storage volume is completely filled with lubricant and thus the rolland the lubricating device can develop their full action.

The lubricant used can normally be a water, to which additives can beadded if appropriate. The pressure in the supply line can be, forexample, between 2 and 8 bar, in particular 4 to 6 bar.

A further idea which, even taken on its own, represents an inventiveachievement but can also be used in combination with a roll according toone aspect of the invention relates to a sealing device for sealing offa positive or negative pressure zone of a roll for a machine forproducing or processing a fibrous web, wherein the sealing device has asealing strip and a lubricating device, by means of which, when used asintended, a lubricant can be introduced between the inside of the rollshell and the sealing surface of the sealing strip, and wherein thelubricating device comprises a plurality of lubricant outlet openingsand can be connected to a supply line for supplying with lubricant. Thesealing device is characterized in that the lubricating device can beconnected to the supply line via a plurality of inlets which aredistributed over the length of the sealing strip, the sealing strip hasa first and a second longitudinal end, and the spacing from at leastone, preferably both, longitudinal ends to an inlet is at most 800 mm,in particular at most 600 mm, preferably 400 mm or less.

As already mentioned, such a sealing device can be used in a rollaccording to an aspect of the invention, that is to say in particular incombination with a supply line which has a storage volume of at least490 cm³/m, in particular at least 500 cm³/m. The inlet segmentsmentioned at the beginning can be connected to the inlets of the sealingdevice described here. However, such a sealing device is alsoadvantageous when considered on its own.

Such a sealing device may in particular be advantageous also to supplythe edges of the sealing strip adequately and uniformly with lubricant.Over the greatest part of the length of the sealing strip, each pointcan be supplied with lubricant both from the left and from the right,since there is at least one inlet on both sides, via which thelubricating device is supplied with lubricant. In the edge regions ofthe sealing strip on the other side of the first and last inlet,however, the problem arises that these regions are supplied withlubricant only from one side, since there is an inlet only on one side.This can lead to the region of the longitudinal ends of the sealingstrip not being supplied with sufficient lubricant, specifically alsowith less lubricant than the central region of the sealing strip.

Advantageous embodiments of such a sealing strip are described below.

Thus, provision can advantageously be made for the inlets to be arrangedsuch that their spacing from one another in the longitudinal directionof the roll is less than 2 m, in particular less than 1.75 m, preferably1.5 m or less. In particular, the inlets can also be arranged such thatthe spacing of adjacent inlets from one another in the longitudinaldirection of the roll is equal or differs only by less than 15%, inparticular less than 5%.

Preferably, the lubricating device can be provided wholly or partly inor on the sealing strip, wherein in particular the lubricant outletopenings can be in the sealing strip.

The invention will be explained in more detail below by using schematicdrawings, the invention not being restricted to these embodiments.

FIG. 1 shows a detail of a roll according to one aspect of the invention

FIG. 2 shows a detail of the roll according to a further aspect of theinvention

FIG. 3 shows a detail of a roll according to a further aspect of theinvention

FIG. 4 shows a detail of a roll according to a further aspect of theinvention.

FIG. 1 shows a roll 1 having a roll shell 11 and an end face 12. Such aroll can be, for example, a suction roll 1. A sealing device 2 isprovided in the interior of the roll 1. The former comprises a sealingstrip 3, which is arranged in a sealing strip holder 3 a, and alubricating device 4. The lubricating device 4 shown in FIG. 1 islargely located in the sealing strip 3. A multiplicity of lubricantoutlet openings 5 are arranged beside one another. These openings 5 areplaced such that the emerging lubricant gets between the sealing surfaceof the sealing strip 3 and the roll shell 11. For the supply of thelubricating device 4 with lubricant, e.g. with lubricating water, asupply line 6 is provided, which comprises an inner section 7 whichextends in the interior of the roll shell 11, and has a storage volumeof at least 490 cm³/m, in particular at least 500 cm³/m, preferably ofat least 2000 cm³/m, based on the length of the sealing strip, and anouter section 8. Via a plurality of inlet segments 9, 9 a, thelubricating device 4 is connected to the inner section 7 of the supplyline 6 at a plurality of inlets 10, 10 a. In advantageous embodiments,the spacings of two adjacent inlet segments 9, 9 a and/or two adjacentinlets 10, 10 a can each be equal. Alternatively or additionally,provision can also be made for the inlet segments 9, 9 a to be arrangedsuch that their spacing from one another in the longitudinal directionof the roll 1 is less than 2 m, in particular less than 1.75 m,preferably 1.5 m or less. The spacing of an inlet segment 9 a or aninlet 10 a from a longitudinal end of the sealing strip 3 can preferablybe at most 800 mm, in particular at most 600 mm, preferably 400 mm orless. Advantageously, the length of the inlet segments can be between150 mm and 700 mm, in particular between 200 mm and 400 mm. It is a veryadvantageous embodiment here when the inner section 7 is mounted on theoutside of the suction box of a negative pressure zone. Firstly, thismounting position is more easily accessible than in the interior of thesuction box. Secondly, the spacing of the inner section 7 of the supplyline to the inlets 10, 10 a of the sealing strip is usually lower, sothat it is possible to manage with shorter inlet segments 9, 9 a with alength of, for example, 150 mm-250 mm.

The inner section 7 of the supply line in FIG. 1 comprises a pipe-shapedpart. This pipe advantageously be made of a material (e.g. metal orplastic) which is more rigid than the inlet segments 9, 9 a. It ispossible, for example, to use pipes having internal diameters of 25 mm(corresponding to a storage volume of about 500 cm³/m), 40 mm or 50 mm(corresponding to a storage volume of about 2000 cm³/m). The inletsegments 9, 9 a can be embodied, for example, as hose segments.

FIG. 2 differs from FIG. 1 in that the inner section 7 consists of apipe 7 which tapers continuously over its length.

FIG. 3 shows a sealing strip 3 in a holder 3 a, which is pressed againstthe inside of the roll shell 11 of the roll 1 by means of a pressurehose 13. Such a use of a pressure hose for pressing onto a movingsurface such as a roll shell is a measure which is usual and known tothose skilled in the art. As distinct from the embodiments shown inFIGS. 1 and 2, in FIG. 3 the lubricating device 4 is not integrated intothe sealing strip. The lubrication is implemented by means of a numberof spray nozzles, which provide the outlet openings 5. The spray nozzlesare connected to the inner section 7 of the supply line via inletsegments 9.

A further advantageous feature which, in FIG. 3, is implemented togetherwith the spray nozzles but which is also possible in combination with alubricating device 4 integrated into the sealing strip 3, consists inthe inner section 7 of the supply line extending at least partly atleast partly on or in the sealing strip holder 3 a. This inner section 7provides the storage volume of at least 490 cm³/m, in particular atleast 500 cm³/m, and can, for example, have the form of a cylinder or atapering cylinder.

In FIG. 4, essential components of the invention are illustrated, oncemore schematically. In a sealing strip 3 with an integrated sealingdevice, the lubricant outlet openings 5 are supplied with lubricant viainlets 10, 10 a. The inlets 10, 10 a are connected to the inner section7 of the supply line via inlet segments 9, 9 a. The inner section 7 isagain embodied as a pipe, which also provides the storage volume. Thespacings of the longitudinal end of the sealing strip 3 from the firstinlet 10 a and from the first inlet segment 9 a are designated by d1 andd5, while the spacings of adjacent inlets 10, 10 a and adjacent inletsegments 9, 9 a from one another are designated by d2, d3, d4. Thenumber of four inlets here is exemplary. It is entirely possible formore or fewer inlets/inlet segments to be provided.

The following table indicates some advantageous spacings of the inletsegments and the inlets.

Example No. d₁ d₂ d₃ d₄ d₅ #1 400 mm 1360 mm 1360 mm 1360 mm 400 mm #2640 mm 1200 mm 1200 mm 1200 mm 640 mm #3 540 mm 1250 mm 1300 mm 1250 mm540 mm

As can be seen in, the “inner” spacings d2−d4 can be equal or differ bya few millimeters. This can be necessitated, for example, by theinstallation situation.

LIST OF DESIGNATIONS

-   1 Roll-   2 Sealing device-   3 Sealing strip-   3 a Holder-   4 Lubricating device-   5 Lubricant outlet openings-   6 Supply line-   7 Inner section-   8 Outer section-   9, 9 a Inlet segment-   10, 10 a Inlet-   11 Roll shell-   12 End face-   13 Pressure hose

1-16. (canceled)
 17. A roll for a machine for producing or processing afibrous web, the roll comprising: a movable roll shell having an innersurface and a positive or negative pressure zone disposed within saidroll shell and fixed against rotation relative to said roll shell; asealing device for sealing off said positive or negative pressure zonefrom the surroundings, said sealing device having a sealing strip with alength and a sealing surface and said sealing device having alubricating device for introducing a lubricant between said innersurface of said roll shell and said sealing surface of said sealingstrip, said lubricating device including a plurality of lubricant outletopenings; a supply line for supplying lubricant, said supply lineincluding an inner section extending within said roll shell, said innersection having a storage volume of at least 490 cm³/m based on saidlength of said sealing strip; and a plurality of inlet segmentsconnecting said lubricating device to said supply line.
 18. The rollaccording to claim 17, wherein said storage volume is at least 2000cm³/m.
 19. The roll according to claim 17, wherein said inner sectionincludes or is formed of a pipe-shaped part extending substantiallyentirely over said length of said sealing strip, said pipe-shaped parthaving an inside diameter of 25 mm or more at least at one location. 20.The roll according to claim 19, wherein said inside diameter of saidpipe-shaped part is more than 40 mm.
 21. The roll according to claim 19,wherein said inside diameter of said pipe-shaped part is 50 mm or more.22. The roll according to claim 19, wherein said pipe-shaped part has alength and a constant cross section over more than 50% of its length orover its entire length.
 23. The roll according to claim 19, wherein saidpipe-shaped part has a length and tapers continuously over its length.24. The roll according to claim 17, wherein said plurality of lubricantoutlet openings are distributed uniformly over said length of saidsealing strip or said plurality of lubricant outlet openings includeadjacent lubricant outlet openings separated by spacings differing byless than 25% from each other.
 25. The roll according to claim 17,wherein said lubricating device is provided wholly or partly in or onsaid sealing strip, or said lubricant outlet openings are formed in saidsealing strip.
 26. The roll according to claim 17, wherein said innersection is at least partly rigid.
 27. The roll according to claim 17,wherein said sealing device includes a holder for holding said sealingstrip, and said inner section extends at least partly on or in saidholder.
 28. The roll according to claim 17, wherein all of said inletsegments have a length being identical to each other or differing byless than 25% from each other.
 29. The roll according to claim 17,wherein said inlet segments have a length of between 150 mm and 700 mm.30. The roll according to claim 17, wherein said inlet segments have alength of between 200 mm and 400 mm.
 31. The roll according to claim 17,wherein said supply line has an outer section extending substantiallyoutside the roll, said outer section having an inside diameter of 25.4mm or less, and said outer section having an end face guided into aninterior of the roll and connected to said inner section.
 32. The rollaccording to claim 31, wherein said inside diameter of said outersection is 12.7 mm or less.
 33. The roll according to claim 17, whereinsaid inlet segments include adjacent inlet segments separated from eachother in a longitudinal direction of the roll by spacings being equal toone another or differing from one another by less than 15%.
 34. The rollaccording to claim 33, wherein said spacings differ from one another byless than 5%.
 35. The roll according to claim 17, wherein said inletsegments are separated from each other in a longitudinal direction ofthe roll by spacings of less than 2 m.
 36. The roll according to claim35, wherein said spacings between said inlet segments are less than 1.75m.
 37. The roll according to claim 35, wherein said spacings betweensaid inlet segments are 1.5 m or less.
 38. A method for operating a rollfor a machine for producing or processing a fibrous web, the methodcomprising: providing a roll according to claim 17; and supplying saidlubricating device with less than 2.4 l/min/m of lubricant.
 39. Themethod according to claim 38, which further comprises supplying saidlubricating device with between 0.4 l/min/m and 1.5 l/min/m oflubricant.
 40. The method according to claim 38, which furthercomprises: supplying the lubricating device with a first quantity oflubricant over a starting time period; and supplying the lubricatingdevice with a second quantity of lubricant after the starting timeperiod; the first quantity of lubricant being greater than the secondquantity of lubricant.
 41. The method according to claim 40, wherein thefirst quantity of lubricant is more than 25% greater than the secondquantity of lubricant.
 42. The method according to claim 38, wherein thestarting time period is at least 30 seconds.
 43. The method according toclaim 38, wherein the starting time period is between 30 seconds and 5min.